Few blooms provide more showy appeal than Hydrangeas: long-blooming, with showers of magnificent clusters of colorful flowers. However, some of us may be wondering why that beautiful pink shrub that we planted last year has now turned a bright shade of blue! Hydrangeas may produce pink, blue, or lavender blooms, depending on where it’s planted and how it’s fed. The presence of aluminum in the plant ultimately determines the color, and pH affects the uptake of aluminum. Alkaline soils, pH of 6.0 or more, are more likely to produce pink blooms, and more acidic soils, pH 4.5 to 5.5, produce blue flowers.

You can change your bloom color to blue, pink or red with acidic or alkaline soil!

• Always test your soil before planting (Soil Test Kits are available online).
• Know your Hydrangea variety: white, panicle, and climbing Hydrangeas do not change color.
• In slightly acid or neutral soil (pH 6 to 7), blooms can be a mix of blue and pink on the same plant.
• If your soil pH is very high (alkaline) it will be harder to lower its concentration. Plant pink and white varieties only.

Acidic Soil (pH below 6) Blue flowers:

• Hydrangeas can be turned blue by applying aluminum sulfate to lower pH, adding available aluminum to the soil for plant uptake. To lower the pH of your soil, add Espoma® Soil Acidifier to alkaline soil by following label directions.

Alkaline soil (pH above 7) Pink or Red flowers:

• Applying lime to raise the pH level will help blue Hydrangeas turn pink. This is done by applying a high phosphorus fertilizer and/or Espoma® Garden Lime according to label directions.

PRO TIP: If your soil naturally produces very blue or very pink hydrangea flowers, you may need to grow your hydrangeas in containers or raised beds to achieve the desired color.

PRO TIP: If you do attempt to change the color of your blooms by adding these minerals, dilute them well, and add sparingly. It is very easy to scorch your plants by adding too much. Always follow the product’s application instructions for the safest and best results.